Zen and the Art of Lawnmower Repair...

Sick push lawnmower. All the facts follow to aid in your deduction (and to help me get my troubleshooting straight in my head). I'll hold my tongue on my thoughts for now and hear what everyone says first.

Bought it used, from a lawnmower repair guy. When I picked it up it started for the guy on the first pull. I've been mowing the lawn with it for months and it has done me well.

Then a couple weeks ago the lawn got away from me. I was out of town the weekend I wanted to mow and it rained too hard the next weekend. On Tuesday or Wednesday I realized the lawn wasn't going to wait until Saturday and I went out and mowed the bastard.

I had to mow in half-passes--leave about half the cutting deck on grass that had already been cut. Even so, the mower was struggling and died a couple times. I started "clunking" the thing at the end of every pass to break loose all the grass that was building up inside the deck (sorta like a lowrider at a stoplight).

Well eventually it starts to sputter like it is choking so I stop pushing, but it doesn't recover, it keeps sputtering and dies. I flipped the thing over and cleaned out all the grass. At that point it would start when I'd pull the cord, then it would sputter out and die. I fucked with the hose from the tank to the carb. I fiddled with the spring linkage to the carb. I monkeyed with the cable from the deadman's switch handle--all with no real results. I let it sit for awhile to cool down, thinking it might be overheated. All with no luck. I'd prime it with the little pump bulb and it would start right up, run a few seconds, and die. Eventually it just started up and started working and I finished the lawn.

Well today I mowed a bit before the thing sputtered out and eventually died. It was out of gas, so I picked up some gas and hoped that was it. It wasn't.

Now I couldn't get it started by futzing with it. If I prime it, it'll start up and run for a second or two. If I flip it on its side to look under it it'll run for 4-5 seconds when I right it again.

Air filter is fine. Forgot to mention taking it off as part of the troubleshooting. I'm actually leaning towards a clogged fuel filter. Or some other clog to the fuel line. Reasoning is that while I was "clunking" the thing to dislodge built-up grass I also dislodged something in the fuel system. (I guess I might've just knocked a hose loose somewhere under the cowlings too.)

Oh, and I also pulled the spark plug and had a look at it. Wouldn't hurt to replace it, but I don't think that's the problem.

I had one of those when I was 20. I may be too old and fat for one now. Just pushing this non-self-propelled one kicks my butt.

It is running again. I hesitate to say "I fixed it". More accurate would be to say that I monkeyed around with it for 45 minutes, at the end of which it started and I mowed the lawn with it. And I only damaged a couple parts. I didn't break anything to the point that I need to replace it.

I needed to get away from the desk but I wasn't ready to go make sales calls today, so I went out back and gave the mower a couple jerks. Now it wasn't even starting up at all.

I disconnected the spark plug for a bit. I screwed about with the deadman switch cable (and managed to crack one of the end dinguses that holds it in place, but not so badly that it failed. I finally crimped off the fuel hose and took the bulb off the bottom of the carb. I expected to find a fuel filter there. Actually that probably WAS the fuel filter now that I type this. Because the bolt that held it in place was brass and it was machined with a drain in it. I didn't manage to round the bolt off too badly, taking it off with a vice grips, but I could see I wouldn't get it back on tight enough without destroying it, so I went out to the car and got the wrenches. Picked the right wrench on the first try!

Oh, the other thing, there's a rubber fuel line from the tank to the carb. It is long enough that it makes a sideways "S". And the mount where it goes into the carb is on a swivel, so I fiddled with that a bit to try and get it at an angle where it gas would flow the best. I must've got something right, because a couple more pulls and it started up.

I haven't entirely ruled out a vacuum problem either, because the couple times I flipped it on its side not much gas came out of whereever the tank breather is and it did die on me once for no reason. I took the gas cap off to start it and it popped right off.

Oh, and the air filter actually is dirtier than I thought. And it is a little damp. I couldn't smell if it was gas because I had gas on everything else at the time.

You probably need a float needle. On the newer carbs, there is not hardly any adjustments. The fact that you can hit the primer and it runs for a bit tells you it is starved for gas, which means its not a stopped up air filter which would make it run rich.
If it were rich (flooding) and died then hitting the primer bulb would flood it more and it should not start. Take the plastic cover off this(there usually is one) and find the carb and take the float bowl off it and see if there is anything in that and check that the needle is not stuck in the carb and the float is working ok. You are a motorcycle guy, don't you know carbs?

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